A propagation of a short optical pulse in nonlinear birefringent fibre is d
escribed by a system of two coupled Schrodinger equations By means of varia
tional Anderson method this system reduces to the system of ordinary differ
ential equations for spatial evolution of pulse parameters. In two ultimate
cases the analytical solutions of the equations are managed to be found. I
t is shown that at some critical power of the input pulse W-c the regime of
propagation changes. For the power exceeding W-c the radiation concentrate
s in one channel. The numerical investigation of the intermediate cases was
done when by the variation of the input pulse power one can achieve the co
mparable effectiveness of the competing processes of dispersion broadening
and nonlinear pulse compression. The numerical simulations show that in the
range of critical values of the nonlinear coupling coefficient the transit
ion takes place to the chaotic phase and amplitude behavior of the coupled
waves of different polarizations. The research is important to understand t
he processes of ultra short digital pulses propagation in optical fibre lin
ks. (C) 2000 Elsevier Science Ltd. All rights reserved.